Appliances powered over sas

ABSTRACT

Methods and structure for powering storage devices over a SAS interface. An exemplary system includes a storage device that includes a receptacle configured to receive a plug that communicates Serial Attached Small Computer Systems Interface compliant signals from a host system. The storage device also includes a microcontroller configured to detect a first power level on a power contact of the receptacle. The storage device further includes a circuit board configured to power up to the first power level via the microcontroller, to receive an inter-integrated circuit communication that indicates a second power level is available, and to power up to the second power level to sufficiently power a storage appliance.

CROSS REFERENCE TO RELATED APPLICATIONS

This document claims priority to, and thus the benefit of an earlier filing date from, U.S. Provisional Application No. 61/847,184 (filed on Jul. 17, 2013) entitled “APPLIANCES POWERED OVER ETHERNET AND SAS”, which is hereby incorporated by reference. This patent application is also related to commonly owned and co-pending patent application ‘TBD (Attorney Docket No. 13-0856; hereinafter the “related patent application”), the contents of which are incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to Serial Attached Small Computer System Interface (SAS) and, more particularly, to a storage device that operates on power derived from a SAS interface.

BACKGROUND

The Power Over Ethernet (POE) standard, described in IEEE standards 802.3af and 802.3at, was originally designed and envisioned to power-up small consumer based terminals and office/home computing devices. POE enables a single cable to provide both data connection and electrical power to devices that use Internet Protocol (IP) connectivity. However POE requires Ethernet or SCSI over IP (iSCSI) interfaces which are not suited for certain systems such as storage servers.

SUMMARY

Systems and methods herein provide for powering devices over a SAS interface. In one embodiment, a storage device includes a receptacle configured to receive a plug that communicates Serial Attached Small Computer Systems Interface compliant signals from a host system. The storage device also includes a microcontroller configured to detect a first power level on a power contact of the receptacle. The storage device further includes a circuit board configured to power up to the first power level via the microcontroller, to receive an inter-integrated circuit communication that indicates a second power level is available, and to power up to the second power level to sufficiently power a storage appliance.

Other exemplary embodiments (e.g., methods and computer readable media relating to the foregoing embodiments) are also described below.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of the present invention are now described, by way of example only, and with reference to the accompanying figures. The same reference number represents the same element or the same type of element on all figures.

FIG. 1 is a block diagram illustrating a SAS topology in an exemplary embodiment.

FIGS. 2 a-b illustrate views of a connector receptacle and plug, respectively, operable with a SAS topology.

FIG. 3 is a power-wire connecting diagram in an exemplary embodiment.

FIG. 4 is a flowchart illustrating a method for powering a storage device over a SAS interface in an exemplary embodiment.

FIG. 5 is a block diagram of an exemplary computing system in which a computer readable medium provides instructions for performing methods therein.

DETAILED DESCRIPTION

The figures and the following description illustrate specific exemplary embodiments of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within the scope of the invention. Furthermore, any examples described herein are intended to aid in understanding the principles of the invention, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the invention is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.

FIG. 1 is a block diagram illustrating a SAS topology 100 in an exemplary embodiment. The SAS topology 100 is used to achieve reliable, high-speed communication between SAS devices in a point-to-point architecture. The SAS topology 100 includes a host system 110 coupled to a storage device 120 via a SAS cable 130. The host system 110 and the storage device 120 include SAS ports 112 and 122, respectively, which are configured to communicate over the SAS cable 130 in accordance with the SAS protocol. A controller 114 of the host system 110 is configured to generate SAS command signals to perform read/write operations on data stored on the storage device 120.

In this embodiment, the SAS ports 112 and 122 include connectors of the SFF-8644 specification, entitled “Mini Multilane 12 Gbs 8/4x Shielded Connector,” which is hereby incorporated by reference in its entirety. In the SFF-8644 specification, the power pin on the SAS port 112 of the host system 110 may apply power (i.e., Vact) to the SAS port 122 of the storage device 120. However, in the SFF-8644 specification, Vact is reserved for active (e.g., longer length) SAS cables and operates at low voltage and low power (e.g., up to 1.5 watts). In other words, using a SAS SFF-8644 connector described in the standard, the host system 110 may power, for example, an optical transceiver using up to 1.5 watts, however, that power level is unable to provide power to larger periphery appliances such as the storage device 120.

The SAS topology 100 is therefore enhanced with SAS ports 112 and 122 that connect each end of the SAS cable 130 with an SFF-8644 connector that is configured to supply sufficient power (e.g., up to 30 watts) to operate the storage device 120 with power supplied over the SAS cable 130 from the host system 110. Thus, the SAS port 112 of the host system 110 is configured to supply data and power in parallel to the SAS port 122 of the storage device 120. Other solutions which implement power and data in parallel (i.e., Power Over Ethernet) use protocols (i.e., Ethernet) which are unsuitable for storage networks.

The controller 114 of the host system 110 is enhanced to communicate the power-supplying ability of the host system 110 to other SAS devices using the inter-integrated circuit (I2C) communication protocol. Furthermore, the microcontroller 124 of the storage device 120 is enhanced to receive I2C communication to determine whether the host system 110 is able to provide sufficient power to operate the storage device 120 over the SAS cable 130. The SAS ports 112 and 122 of the SAS topology 100 are therefore configured to use I2C 132 for communicating power ability and permission to extend Vact 134 to its full range of power (e.g., up to 30 watts in the SFF-8644 specification).

Suppose, for example, that the cable 130 is a size 24 according to the American Wire Gauge (AWG) standard. A connector in accordance with the SFF-8644 standard provides 0.5 amps per connector (2 pins) at 30 volts for a total power of 30 watts. Assuming a 5 watt loss budget at 0.08422 watts/meter, the configuration described herein is operable to provide up to 25 watts (i.e., 30 watts-5 watts) for up to approximately 60 meters (i.e., 5/0.08422). Thus, the configuration described is able to provide power over a SAS (POS) connection (i.e., data and power over a single SAS cable) and selectively power up/down the storage device 120 (which may be powered with 25 watts) via the host system 110.

The controller 114 of the host system 110 may include a host bus adaptor (HBA), that may be a stand-alone device or included as a component in the host system 110. Examples of storage devices 120 include, but are not limited SAS hard disk drives, SATA hard disk drives, etc. The host system 110 may include one or more of Serial SCSI Protocol (SSP) ports typically used to communicate with SAS drives, Serial ATA Tunneling Protocol (STP) ports typically used to communicate with SATA drives, and/or Serial Management Protocol (SMP) ports typically used to communicate with expanders in an SAS domain.

It will be appreciated that the particular arrangement, number, and configuration of components described herein is exemplary and non-limiting. For example, SAS topology 100 may implement any number of host systems, storage devices, and associated communication paths. Furthermore, SAS topology 100 may implement one or more expanders expand the number of ports used to interconnect one or more host system(s) 110 with one or more storage device(s) 120. The storage device(s) 120 may be either standard SCSI protocol SAS devices or may be SATA protocol devices coupled through the SAS domain.

FIG. 2 a-b illustrates views of a connector receptacle 200 and plug 250 operable with a SAS topology. The receptacle 200 and plug 250 comprise Mini-SAS connectors of the SFF-8644 specification. The SAS ports 112 and 122 of the host system 110 and storage device 120, respectively, may therefore implement the receptacle 200 shown in FIG. 2 a. Similarly, each terminal end of the SAS cable 130 may implement the plug 250 shown in FIG. 2 b. The receptacle 200 and plug 250 include four groups of pins A-D. FIG. 3 is a power-wire connecting diagram operable with the Mini-SAS connectors 200 and 250 in an exemplary embodiment. As shown, each group of pins A-D collectively provide ground pins and signal pins (e.g., RX0+, RX0−, TX0−, and TX0+, etc.). More particularly, pins B1 and D1 provide power Vact 134, and pins C1 and C1 are the communication pins configured to determine whether the host system 110 is configured to supply enough power for the storage device 120.

FIG. 4 is a flowchart illustrating a method for powering a storage device over a SAS interface in an exemplary embodiment. In step 202, the SAS port 122 of the storage device 120 receives a plug (e.g., cable 130) that communicates SAS compliant signals from the host system 110. In step 204, the microcontroller 124 of the storage device 120 detects a first power level on a power contact of the SAS port 122. In other words, the microcontroller 124, being integrated with the SAS port 122, detects power available on Vact 134 (i.e., pin B1 and D1) supplied from the host system 110. In one embodiment, the first level of power is 1.5 watts since that is a power level that is used for powering optical transceivers in the SFF-8644 standard. In another embodiment, the microcontroller 124 comprises a low power microcontroller so that minimal energy is expended by the host system 110 to enable the storage device 120 to detect available power levels.

In step 206, the microcontroller 124 powers up a circuit board of the storage device 120 to the first power level when it is available from the host system 110. Thus, in one embodiment, the microcontroller 124 uses up to 1.5 watts from Vact 134 if it is available from the host system 110. In step 208, the microcontroller 124 receives an I2C communication that indicates a second power level is available from the host system 110. When the second power level is available, the microcontroller 124 powers up the circuit board of the storage device 120 to sufficiently power a storage appliance. The I2C communication may be received from the host 110 via pins C1 and C2 to indicate to the microcontroller 124 of the storage device 120 to power the storage device 120 via pins B1 and D1.

Embodiments disclosed herein can take the form of software, hardware, firmware, or various combinations thereof. In one particular embodiment, software is used to direct controller 114 and/or microcontroller 124 to perform the various operations disclosed herein. FIG. 5 illustrates an exemplary processing system 500 operable to execute a computer readable medium embodying programmed instructions. Processing system 500 is operable to perform the above operations by executing programmed instructions tangibly embodied on computer readable storage medium 512. In this regard, embodiments of the invention can take the form of a computer program accessible via computer readable medium 512 providing program code for use by a computer (e.g., processing system 500) or any other instruction execution system. For the purposes of this description, computer readable storage medium 512 can be anything that can contain or store the program for use by the computer (e.g., processing system 500).

Computer readable storage medium 512 can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor device. Examples of computer readable storage medium 512 include a solid state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), and DVD.

Processing system 500, being suitable for storing and/or executing the program code, includes at least one processor 502 coupled to program and data memory 504 through a system bus 550. Program and data memory 504 can include local memory employed during actual execution of the program code, bulk storage, and cache memories that provide temporary storage of at least some program code and/or data in order to reduce the number of times the code and/or data are retrieved from bulk storage during execution.

Input/output or I/O devices 506 (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled either directly or through intervening I/O controllers. Network adapter interfaces 508 can also be integrated with the system to enable processing system 500 to become coupled to other data processing systems or storage devices through intervening private or public networks. Modems, cable modems, IBM Channel attachments, SCSI, Fibre Channel, and Ethernet cards are just a few of the currently available types of network or host interface adapters. Display device interface 510 can be integrated with the system to interface to one or more display devices, such as printing systems and screens for presentation of data generated by processor 502. 

What is claimed is:
 1. A storage device, comprising: a receptacle configured to receive a plug that communicates Serial Attached Small Computer Systems Interface compliant signals from a host system; a microcontroller configured to detect a first power level on a power contact of the receptacle; and a circuit board configured to power up to the first power level via the microcontroller, to receive an inter-integrated circuit communication that indicates a second power level is available, and to power up to the second power level to sufficiently power a storage appliance.
 2. The storage device of claim 1, wherein: the inter-integrated circuit communication indicates that up to 30 watts is available from the host system.
 3. The storage device of claim 1, wherein: the plug comprises a High Density Mini Serial Attached Small Computer System Interface plug.
 4. The storage device of claim 1, wherein: the receptacle comprises a High Density Mini Serial Attached Small Computer System Interface plug.
 5. The storage device of claim 4, wherein: power is received on pins B1 and D1 of the receptacle.
 6. The storage device of claim 4, wherein: the inter-integrated circuit communication is received via pins C1 and C2 of the receptacle.
 7. The storage device of claim 1, wherein: the plug is a terminal end of a size 24 American Wire Gauge standard cable; and the cable delivers up to 25 watts of power from the host system to the storage device to power the storage device from a distance of up to 60 meters.
 8. A method, comprising: receiving, with a receptacle of a storage device, a plug that communicates Serial Attached Small Computer Systems Interface compliant signals from a host system; detecting, with a microcontroller, a first power level on a power contact of the receptacle; powering up a circuit board of the storage device to the first power level via the microcontroller; receiving an inter-integrated circuit communication that indicates a second power level is available; and powering-up the circuit board to the second power level to sufficiently power a storage appliance.
 9. The method of claim 8, wherein: the inter-integrated circuit communication indicates that up to 30 watts is available from the host system.
 10. The method of claim 8, wherein: the plug comprises a High Density Mini Serial Attached Small Computer System Interface plug.
 11. The method of claim 8, wherein: the receptacle comprises a High Density Mini Serial Attached Small Computer System Interface plug.
 12. The method of claim 11, wherein: power is received on pins B1 and D1 of the receptacle.
 13. The method of claim 11, wherein: the inter-integrated circuit communication is received via pins C1 and C2 of the receptacle.
 14. The method of claim 8, wherein: the plug is a terminal end of a size 24 American Wire Gauge standard cable; and the cable delivers up to 25 watts of power from the host system to the storage device to power the storage device from a distance of up to 60 meters. 